This invention relates generally to mobile chairs and specifically to a power chair that is lightweight, capable of manual operation and easily transportable.
There are basically two types of mobile chairs; conventional, hand propelled wheelchairs and chairs that are powered (motorized), either by a battery or a gasoline engine. The term motorized as used herein is intended to apply to both battery power and engine power. Hand propelled wheelchairs have been manufactured for more than a century without significant changes in design. Generally hand rings are mounted adjacent to the large wheels to assist in propulsion by the user, although very often the wheel tires are grasped directly to propel the wheelchair. Such wheelchairs are satisfactory for indoor use where floors are usually flat and smooth. Outdoor operation on the other hand, presents challenging obstacles for a user. For example, soft ground and hills make it extremely difficult to travel with a hand propelled wheelchair. Therefore, some sort of powered wheelchair is considered very beneficial for outdoor use.
Most powered wheelchairs and powered scooters are battery driven and intended for outdoor as well as indoor use, but they are not suited to unpaved surfaces like grass, dirt and bumpy trails. The shopping cart scooter is the most popular and, while designed primarily for indoor use, it also sees limited outdoor service in transporting both the user and groceries across the store parking lot. Powered wheelchairs and scooters have been a boon to the handicapped and elderly. Most battery powered wheelchairs use two motors, left and right, each being associated with some form of reduction gearing. A joystick controls a fairly complicated electronic system for switching and modulating the requisite high current, low voltage, power. These arrangements are expensive and prone to service problems.
Scooters on the other hand, use only one motor which drives the wheels through a differential. While the costs and weight of a differential are about the same as an extra motor and gear reduction mechanism, the controls on the scooter are less complicated and the unit is generally more reliable than the two motor wheelchair. Steering of the front wheel of the scooter is accomplished with a small handlebar. Unfortunately, the scooters are not particularly maneuverable. These vehicles' major drawbacks of bulk and weight (generally in the range of 150 to 200 pounds), have prevented their widespread acceptance and use despite their obvious great benefits for outdoor use. They also require special measures in order to transport them.
One serious drawback is that the motors drive the wheels through gearing which cannot be overdriven. Thus a drive failure, or a dead or defective battery, can leave the 200 pound vehicle frozen in place with its wheels effectively locked and the user helplessly stranded. Generally a van, which has a large door, rather than a passenger automobile, is required to transport them. The van is usually equipped with a power lift of some sort to enable the loading and unloading of the motorized powered chair or scooter.
The present invention provides a power chair that is lightweight, compact and maneuverable and therefore well suited to hand propulsion. The preferred embodimnent of the invention is directed to a powered wheelchair, but it will be apparent that the invention will find ready use as a safe, transportation vehicle for use by all ages, irrespective of any infirmity. It's lightweight and small size enables it to be transported by automobile or van without special equipment and its long range permits it to be used in the country for sightseeing and the like.
While the preferred embodiment incorporates a compact gasoline engine, it should be understood that the invention is not to be so limited. The particular compact gasoline engine used is a 4-cycle Honda.RTM. engine, which finds application in hand equipment such as electric generators, water pumps, chain saws and weed trimmers. The engine is much lighter than a comparably sized electric motor, and is much quieter and cleaner burning than the 2-cycle engines normally used in such equipment. Whereas most battery powered chairs weigh from 150 to 200 pounds, and a conventional hand propelled wheelchair weighs around 40 pounds, the powered wheelchair version of the invention weighs only 35 pounds. As will be seen, the inventive power chair also employs a comfortable, removable, padded rigid seat, which, when removed, enables the power chair to be transported in the trunk of a compact automobile. In contrast, conventional hand powered, transportable wheelchairs require a flexible sling type seat and back, which are not comfortable for the user.
As mentioned above, the power chair of the invention is readily transportable in the trunk of a compact automobile and is easily hand propelled, when indoors, because of its lack of bulk, extreme light weight and excellent maneuverability. The gasoline powered version of the inventive power chair is presently preferred since it exhibits a much greater range of operation (approximately 45 miles per 1/2 gallon tank of gasoline) over a battery powered power chair of the same general design. Refilling the 1/2 gallon tank is also much faster and more convenient than recharging a battery from a household source of power.
Propulsion and steering of the inventive power chair is provided by selectively engaging the wheels with corresponding motor-driven friction rollers that are affixed to a rotatable drive axle. The engagement between the friction rollers and the wheels is controlled by a pair of manual control arms that the user moves forward for propulsion and backward for braking. This action is accomplished by a pivotally mounted rocker lever that carries a friction drive roller and a friction brake surface that are selectively engageable with the associated wheel. Normal turning is accomplished by engaging one friction roller with its corresponding wheel. Very tight turns may be made by simultaneously engaging one friction roller with its associated wheel and engaging the other brake surface with its associated wheel. Since the control arm arrangements are self centering, the wheels are normally in a free wheeling state.
In one version of the inventive power chair, provision is made for "hands free" steering through the use of a clutched drive lock system for holding both friction rollers in engagement with the wheels for forward propulsion. The clutched drive lock system also provides a "parking brake" to hold the power chair on inclined surfaces or to steady it for the user. The maneuverability of the inventive power chair derives from the transmission system discussed above and the provision of a front caster wheel that freely swivels in accordance with the directional forces developed by the wheels. The freely movable front caster wheel is also provided with a foot steering plate, generally for making slight steering corrections to compensate for road conditions and the like and is especially useful for hands free operation during relatively long distance travel, when the clutched drive lock system is engaged. As will be seen, the transmission system, including the motor, is movably supported on the power chair frame to permit the pivoting and translational movements of the drive axle.